Restorative therapy clinical trials for erectile dysfunction: a scoping review of endpoint measures

Given the lack of regulatory approval for restorative therapies for the treatment of erectile dysfunction, we hypothesized that clinical trials would vary in methodology and endpoint measurements. Our objective was to analyze methodological approaches and outcome measures of clinical trials evaluating restorative therapies for erectile dysfunction. Data was extracted from clinicaltrials.gov on trials which contained the keywords "erectile dysfunction". We evaluated trials initiated between 2004 and 2021 which listed a restorative therapy intervention. We identified 95 trials investigating energy-based/shockwave therapies (60/95), stem cell therapies (25/95), platelet-based therapies (6/95), and others (4/95). Only 41.1% of the trials evaluated safety. The most common efficacy endpoint was International Index of Erectile Function and Sexual Health Inventory for Men, and only 29.5% utilized penile Doppler. Thirty (31.6%) trials had been completed yet only 3 (3.2%) have published results. We found substantial heterogeneity in methodological approach in the trials. Subjective measures of erectile function were commonly reported, but definitions of inclusion criteria and objective outcome measures were inconsistent. These results provide a basis for the design of future clinical trials to improve the quality of trial data and aid in the development of standardized criteria for erectile dysfunction clinical trials.